1. Field of the Invention
The present invention relates to an improved device for fixing in place a prosthetic device in the human mouth and a method for producing the same.
2. Description of Related Art
A superior dental adhesive product has been commercially available under the trademark SEA-BOND(copyright) and is used in the human mouth to bond a denture to the soft gum tissues. As described in U.S. Pat. No. 4,503,116, the disclosure of which is incorporated herein by reference, the dental adhesive is a laminate of webs having a carrier portion with fibers thermoplastically bonded together by an interposed layer of ethylene oxide polymer powder. The ethylene oxide polymer powder is a dry, water-activated adhesive.
Accordingly, the thermoplastic properties of the ethylene oxide polymer make a better laminate and its water-activated adhesive properties improve the laminate denture fixability. Such fixative properties are further improved by admixing another dry, water-activated adhesive material, such as sodium alginate, with the ethylene oxide polymer powder to promote formation of a gel-like adhesive mass between the denture plate and the mouth tissue.
The dental adhesive product disclosed in U.S. Pat. No. 4,503,116 contains a fiber-faced web which is formed by arranging a layer of loose synthetic fibers on a carrier such as a cellulosic paper. The loose fibers are passed through the carrier by needle-punching them so the fibers protrude from either side of the paper. A pair of such fiber-faced carriers are heat- and pressure-bonded together by the thermoplastic powder layer, such as ethylene oxide polymer powder to which a dry powder fixative, such as sodium alginate, has been added.
A thin version of this dental adhesive is disclosed in U.S. Pat. No. 4,632,080, the disclosure of which is also incorporated by reference into this disclosure. This thin version comprises web laminates of thin edible papers.
U.S. Pat. No. 5,624,745, the disclosure of which is also incorporated by reference, describes a further improved laminate dental adhesive in which ethylene oxide polymer is applied as a pre-cast film, not as a powder.
Finally, U.S. Pat. No. 5,658,586 discloses a denture adhesive composition comprising one or more water soluble adhesive components and at least one non-adhesive self-supporting layer. The patent discloses that the denture adhesive composition can also comprise a coating on one side that is sticky to dry dentures.
While some of the resulting products have enjoyed great commercial success, further improvements are desired.
In particular, as described above the adhesive component of the prior art laminates is sandwiched between two fibrous material scrim. The adhesive is activated by moisture and diffuses through the scrim to form a sticky coating on the outside of the laminate. The holding power of the dental adhesive product is therefore somewhat limited by the ability of activated adhesive to form on the exterior surface of the laminate and establish a bond between the denture and the oral cavity.
It is therefore desirable to improve the adhesive action of the laminate product to provide a stronger bond between the denture and oral cavity and to make the adhesive mixture on the exterior surface of the scrim immediately available without the need for diffusion through the layers.
Accordingly, it is an object of the present invention to provide a dental adhesive product having an improved adhesive action to form stronger and more lasting bonds between the denture and the oral cavity.
It is another object to provide an improved dental adhesive product which is readily manufactured.
These and other objects and advantages are obtained by the dental adhesive product and methods of this invention.
Thus, the invention provides a dental adhesive product comprising a laminate of a pair of superimposed fiber-faced webs, each web having an external and an internal surface with fibers held therein and protruding therefrom to present a fiber facing on each surface of each of said webs, a first ethylene oxide polymer composition sandwiched between said internal surfaces of said webs, and a second ethylene oxide polymer composition dispersed on said external surface of at least one of said webs.
The invention also provides method for producing a dental adhesive product comprising:
a) applying a first thermoplastic ethylene oxide polymer composition to a surface of a first fibrous web;
b) contacting the first web with a second fibrous web in superimposed relation to form a composition whereby said first ethylene oxide polymer composition is arrayed between and contacts said first and second webs;
c) applying a second thermoplastic ethylene oxide polymer composition to at least one surface of the first or second webs opposite to the surface contacting the first ethylene oxide polymer composition; and
d) forming a unitary laminate of said first and second ethylene oxide polymer compositions and said first and second webs.
The invention further provides a method for producing a dental adhesive product comprising:
a) applying a first thermoplastic ethylene oxide polymer composition to a surface of a first fibrous web;
b) contacting the first web with a second fibrous web in superimposed relation to form a composition whereby said first ethylene oxide polymer composition is arrayed between and contacts said first and second webs;
c) forming a first unitary laminate of said first ethylene oxide polymer composition and said first and second webs;
d) applying a second thermoplastic ethylene oxide polymer composition to at least one surface of said first unitary laminate; and
e) forming a second unitary laminate from said second ethylene oxide polymer composition and said first unitary laminate.
In one aspect a dental adhesive product is obtained by applying an external coating comprising at least a thermoplastic ethylene oxide polymer to at least one surface of a fibrous web of a denture adhesive product. Heat and pressure are thereafter applied, inter alia, to deform the ethylene oxide polymer coating and thereby thermoplastically bond the external coating to the web(s) as a unitary structure.
The external coating of ethylene oxide polymer can be applied as a powder to a pre-existing dental adhesive product prepared as described above and then bonded thereto to form the improved product. Alternatively, and as more fully described herein, the external coat can be applied to a scrim surface prior to thermoplastically bonding a pair of webs with an interposed layer of dental adhesive. After lamination, the resulting assembly is a dental adhesive laminated product which has improved mechanical properties and which forms a more durable, stronger seal between the gum and denture plate.
While ethylene oxide has been known as a water-activated adhesive, the invention contemplates advantageously using its thermoplastic and film-forming properties in an external coating to make a better laminate and to improve the laminate""s denture fixative abilities. Moreover, such fixative properties may be further improved by employing additional water-activated adhesive material in the ethylene oxide polymer matrix present in the external coat or on the internal sandwiched layer or by dispersing additives such as gums, and the like, in the polymer matrix. Such embodiments further promote the formation of a gel-like adhesive mass between the denture plate and the mouth tissue.
It is also contemplated that synthetic fibers can be punched transversely through the webs. The free, internal ends of the fibers are commingled by entangling and mechanically interlocking the free ends of the fibers. Such a step may be employed just before the superimposed webs pass between heated calender rolls. Accordingly, even greater bonding between the webs is achieved by the interlocked fibers.
The invention may be more completely understood by the following detailed description and the drawings of the preferred embodiment referred to therein.